The present invention relates to a pendulum device or unit for use with a battery-powered clockwork mechanism. The clockwork mechanism may be of a conventional type having, for example, a balance wheel or a quartz crystal to control its timekeeping. A detachably connectable pendulum unit is provided which may readily be attached to the clockwork mechanism and, when this is done, electrical connections are provided from the battery on the clockwork mechanism to a control coil system which operates the pendulum. The pendulum operates entirely independently of the clockwork mechanism in the sense that it does not in any way control the timekeeping function of such mechanism nor is its operation affected by the timekeeping apparatus of the clockwork mechanism.
It is known in the art to provide a battery-powered pendulum clock with a permanent magnet being supported on the pendulum and cooperating with a fixed control coil which is energized to provide a driving impulse on the permanent magnet so as to maintain the oscillations of the pendulum. The oscillations of the pendulum are then transmitted to a wheel mechanism which drives the hands of the clock.
Pendulum clockworks of the kind described can only be used for certain types of clocks. Because the pendulum must have a predetermined period, it is not practical to provide different pendulum lengths with a given clockwork mechanism. Also, where the pendulum length is short, the operating characteristics of such a pendulum clock are relatively poor. Such clocks are highly sensitive to mechanical factors such as, for example, the inclination of the clock, shocks, variations in bearing friction, temperature expansion of the pendulum, etc.
It is also known in the prior art to provide a battery-powered clockwork using a so-called "blind" pendulum. In such a clock, the time-determining mechanism comprises a balance wheel swing system, and with the pendulum serving merely as a dummy pendulum. The pendulum in such clocks is driven mechanically via a wheel of the watch mechanism, the wheel being provided with pins. It is a disadvantage in the design of such clocks that only a predetermined size of pendulum can be used so that its period will be properly related to the pendulum driving mechanism operated by the clockwork. Also, in such types of pendulum clocks, the energy consumption for operating the pendulum is relative great, and the clockwork mechanism must therefore be specially designed for this.